ARM R4F, r1p3 Debug register interface, Coprocessor registers, 11.3.2 CP14 access permissions

Debug

11.3Debug register interface

You can access the processor debug register map using the APB slave port. This is the only way to get full access to the processor debug capability. ARM recommends that if your system requires the processor to access its own debug registers, you choose a system interconnect structure that enables the processor to access the APB slave port by executing load and stores to an appropriate area of physical memory.

This section describes:

•Coprocessor registers

•CP14 access permissions

•Coprocessor registers summary

•Memory-mapped registers on page 11-6

•Memory addresses for breakpoints and watchpoints on page 11-7

•Power domains on page 11-8

•Effects of resets on debug registers on page 11-8

•APB port access permissions on page 11-8.

11.3.1Coprocessor registers

Although most of the processor debug registers are accessible through the memory-mapped interface, there are several registers that you can access through a coprocessor interface. This is important for boot-strap access to the register file. It enables software running on the processor to identify the debug architecture version that the device implements.

11.3.2CP14 access permissions

By default, you can access all CP14 debug registers from a nonprivileged mode. However, you can program the processor to disable user-mode access to all coprocessor registers using bit [12] of the DSCR, see CP14 c1, Debug Status and Control Register on page 11-14for more information. CP14 debug registers accesses are always permitted when the processor is in debug state regardless of the processor mode.

Table 11-1shows access to the CP14 debug registers.

Table 11-1 Access to CP14 debug registers

Debug state	Processor mode	DSCR[12]	CP14 debug access
Yes	X	X	Permitted
No	User	b0	Permitted
No	User	b1	Not permitteda
No	Privileged	X	Permitted

a.Instructions attempting to access CP14 registers cause the processor to take an Undefined exception.

11.3.3Coprocessor registers summary

Table 11-2 on page 11-6shows a set of valid CP14 instructions for accessing the debug registers. All CP14 instructions not listed are Undefined.

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